1. Field of the Invention
This invention relates to rigging equipment. More particularly, it relates to lifting beams for use with hoists and cranes.
2. Description of the Related Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
Lifting beams, spreader beams and truss beams are intended to balance and support a load by providing multiple lift points. Top and bottom flange stiffeners are added to strengthen the beam laterally in case of sideward movement caused by shifting of the load.
Lifting beams are often used in low headroom applications, and are structurally able to handle the load throughout the beam spread. Beams allow multiple point pick up of the load for balance or support purposes. Beams can be used from two hoists to increase lift capacity.
In a fixed hook lifting beam, a horizontal beam supports the load by spreading the lift points and transmits the vertical forces to the crane hook.
An adjustable hook lifting beam has multiple hook locations that allow the beam to accommodate a range of spreads. It is designed to have the capability of handling offset loads by placing hooks at asymmetric hole locations.
A twin bail lifting beam has two lift loops which increases lifting capabilities by making use of two hoists.
Lifting beams must often be custom fabricated for a particular lift that is to be performed. The modular lifting beam of the present invention permits a lifting beam to be assembled from modular components thereby increasing its versatility.
U.S. Pat. No. 7,478,852 describes a lifting apparatus which includes an I-beam having a lower flange and an upper flange; a plurality of hoist connectors positioned on the I-beam extending upwardly from the upper flange; a center load connector positioned on the I-beam extending downwardly from approximately a midpoint along the lower flange; and at least two movable load connectors positioned on the I-beam extending downwardly from the lower flange, each movable load connector engaged with the I-beam by a plurality of support members having one or more wheels positioned to roll along upper surfaces of the lower flange, the center load connector being positioned between the at least two movable load connectors. An associated method described in this patent includes providing the lifting apparatus; connecting a lifting machine to at least one of the hoist connectors; connecting a load to at least one of the load connectors; and lifting the load by using the lifting machine.
U.S. Pat. No. 7,165,908 describes an arrangement of telescoping lifting beams. Two telescopic lifting beams are loaded in their protruded position and are driven from a retracted position to a protruded position. In order to improve the bending strength of the lifting beams, the lifting beams are surrounded by two telescopic tubes, one of the tubes being fixed to the outer end of the telescopic first lifting beam and is slideable on the second telescopic tube, which extends inwardly on the second lifting beam.
U.S. Pat. No. 7,017,963 describes a counter-weighted lifting beam designed to lift and permit balancing of heavy loads. The lifting beam includes an internal counterweight that is adapted to be hydraulically adjusted by use of a manually operated control mechanism. The lifting beam also includes a rigid elongated lifting tower to add stability to the lifting beam and includes a centralized storage cabinet, which stores control mechanism and increases the weight concentration and the overall stability of the beam. Storage batteries and hydraulic control equipment are fully encased in the storage cabinet. As the lifting beam is held by the crane cable and a swivel, the beam can be moved in three dimensions.
U.S. Pat. No. 6,048,012 describes a self-leveling lifting beam adapted to be connected to the boom of crane to assist in the transport of a load to a high-rise building construction. The lifting beam works on the principle of an internal counterweight that is adapted to be hydraulically adjusted, and the use of electric limit switches to automatically maintain horizontal equilibrium even if a load shift occurs in mid-air. Storage batteries are encased in the apparatus to avoid the need for an attached electrical source. The lifting beam is held by the crane cable and a swivel such that the beam can be moved in all three dimensions.
U.S. Pat. No. 4,128,267 describes a lifting beam comprising an elongate member carrying one or more pivotally mounted hooks for engagement of a load to be lifted with a balance weight pivotably mounted on each hook to lie on either side of the pivotal axis thereof so as to cause the hook to be biased into or from engagement with the load such that selection of the position of the balance weight enables the beam automatically to pick up or release the load when the beam is lowered onto it.